Semiconductor devices typically include patterned layers of electrically conductive, non-conductive and semi-conductive materials stacked over a silicon wafer. The various layers of material are successively deposited on the wafer and etched into predefined patterns to form individual component structures within the particular device being fabricated. Chemical vapor deposition (“CVD”) reactors are commonly used for depositing layers of material by introducing select reactant gases into a controlled environment surrounding the wafer. One type of CVD reactor, referred to herein as a gas blanketed down-flow reactor, introduces the reactant gases downward through vertical channels over a wafer positioned horizontally beneath the channels. One such CVD reactor are the Watkins Johnson Company Models WJ-996, WJ 999R 3.3 and WJ 999R 3.5. In this type of CVD reactor, a conveyor belt moves the wafers through an elongated box like chamber called a “muffle.” The conveyor belt travels along and is supported by the lower surface of the muffle. Multiple chemical vapor deposition chambers are located within the muffle. A modular gas injector assembly is positioned at each deposition chamber. The gas injector assembly introduces reactant gases into the deposition chamber. The wafers on the conveyor belt travel through each deposition chamber wherein the surface of the wafer is exposed to the gases and coated with the desired materials. Each gas injector assembly includes an array of plenums and passageways for properly mixing and directing the gases to the surface of the wafers. The injector assemblies also include exhaust ports for removing chemical vapors from the deposition chamber.
During the deposition process, deposition material residue collects on the conveyor belt and on the lower surface of the muffle within the deposition chambers. The residue is continuously removed from the conveyor belt by passing the belt through an etching station outside the muffle. Excessive residue build-up on the lower surface of the muffle can cause the conveyor belt to move unevenly through the deposition chambers, thereby adversely affecting the uniformity of the materials deposited on the surface of the wafers. Consequently, the reactor is periodically shut down to remove the residue that has collected on the lower surface of the muffle. During this shutdown, the conveyor belt is removed from the muffle and the gas injector assemblies are replaced with etch injector assemblies. Presently, so far as applicant is aware, etch injector assemblies for gas blanketed down-flow type reactors such as the Watkins Johnson models noted above are constructed to introduce a vaporized etchant into the deposition chamber and on to the exposed lower surface of the muffle to etch away the deposition material residue. In order to reduce the time necessary to clean the muffle and thereby minimize the time the reactor is out of production, it is desirable to use a liquid etchant to remove the residue from the muffle. The present invention is directed to the etch injector assembly that allows for the introduction of a liquid etchant into an etch chamber and on to the lower surface of the muffle to more rapidly remove deposition material residue from the muffle.